Stock guide and power control for electric furnaces



y 1949. H. A. STRICKLAND, JR 2,468,789

STOCK GUIDE AND POWER CONTROL FOR ELECTRIC FURNACES Filed July 9, 1945 2 Sheets-Sheet l IIIIIIA'IIII;

I i/Ii/Il/I/ll.

INVENTOR garold A. 5' trz'cklandrfi' ATTORNEY May 3, 1949. H. A. STRICKLAND, JR ,7

STOCK GUIDE AND POWER CONTROL FOR ELECTRIC FURNACES Filed July 9, 1945 2 Sheets-Sheet 2 .Ffg. 2.

ATTORNEY Patented May 3, 1949 STOCK GUIDE AND POWER CONTROL FOB ELECTRIC FURNACES Harold A. Strickland, Jr., Detroit, Mich, assignor, by mesne assignments, to The Ohio Crankshaft gogipany, Cleveland, Ohio, a corporation of Application July 9, 1945, Serial No. 603,770

4 Claims. (01. 219-47) This invention relates to stock guide and power means for electric furnaces.

In applicant's copending application Serial No. 477,749, filed March 2, 1943, Patent 2,402,852, issued June 25, 1946, on Induction furnace load control, and assigned to the assignee of the present application, there is described and illustrated a load switch which is placed at the inlet or mouth of end of an induction coil furnace and which is subject to the pressure of the load as it is inserted or removed from the furnace chamber. This load switch is included in the control circuit for the furnace and is intended to function in such a manner that its closure, which may be temporary or permanent, during the heating cycle of a load, is a prerequisite to the heating action of the furnace.

A difllculty in the use of such a front load switch such as described in the above referred to application develops from the fact that the size or diameter of the workpiece entering the furnace chamber may vary from time to time and since it is necessary to center the workpiece for each treatment so that there may be uniformity in heating, it is apparent that the distance of the base surface of the load from the operating member of the fixed load switch will vary. Consequently for certain sizes of load the switch will not properly function.

The outstanding object of the present invention is to provide a load switch unit which will operate correctly irrespective of the diameter of the load. Additional objects of the invention pertain to structural arrangements of the load switch which facilitate accuracy in the operation and simplicity in the assembly of the mechanism, and other attributes such as may appear from consideration of the following description and the accompanying drawing, in which Figure 1 is an elevation partly in section of the front end of a coil inductor heating furnace revealing the relationship of the load switch to the mouth or inlet of the furnace;

Figure 2 is a front view of the showing of Figure 1;

Figure 3 is a section along lines 3-3 of Figure 1 showing a top view of the switch operating mechanism; and 1 Figure 4 is a section along lines 4-4 of Figure 1 showing the spring mechanism for operating the switch lever.

In Figure 1 the numeral I indicates a heating coil furnace section in which the primary elements consist of the tubular heating coil 2 having an outer insulating and protective coat 3 of Transite or the like, a cylindrical heat resistant structure 4 of fire brick 5 with intervening supporting rails 6, and an intermediary insulation layer 1 between the refractory cylinder 4 and the heating coil. The insulation layer preferably is double in formation and may consist of a glass fabric or a composition including mica or other heat withstanding and electrically insulating substance. The rails 6 are preferably provided with load supporting and guiding lugs 8 fastened to the inner surface of the rails and projecting inwardly toward the furnace center. The coil 2 is preferably insulated by taping of glass fabric or other insulating means and a terminal insulation is also provided as indicated by the numeral 9.

There is provided an end plate ill of heat resisting material such as Transite for affording a support for the various mentioned elements. The refractory cylinder 4 projects through an opening formed centrally of this end plate and the rails external to the opening are outwardly turned and provided also with supporting members II with attaching elements l2 binding the members H to the end plate. The end plate l0 and the similar plate at the other end of, the coil (not shown) are bound together by the connecting rod It as indicated in Figure 1,

Positioned axially in extension of the furnace center is a feed guide l4 which consists of a flattened ring l5 centrally perforated and having side finger extensions l6 which are spaced from each other and terminated at a point adjacent the inlet opening of the furnace chamber. The inner edges of the finger ends define an envelope which may be a circle or other figure which corresponds to the type of workpiece .ross section. It is apparent that when a load comprising usually a cylindrical bar is placed with one end within the guide opening, the fingers will direct movement of the bar end to the furnace chamber inlet. Moreover, it will be seen that if the feed guide 14 be shifted laterally of the plane of its face ring l5, usually vertically, the position of the guide element relative to the furnace chamber will be changed to the extent of the shifting. Consequently, provision is made for such shifting by overlapping the plate l5 of the feed guide onto the casing ll of the furnace through an aperture including the feed guide, so that, as desired, the guide may be moved laterally to accommodate itself to different stock diameters.

The furnace coil unit is maintained in fixed position by means of a C-clamp 20 which is pivotally mounted upon a support 2| extending from the base 22 of the furnace, this base supporting also the casing plate H to which the feed guide is secured. The C-clamp includes dual support elements 23 on either side of the central base line of the furnace cylinder and a top clamp member 24 provided with a pressure element 25 retained yieldably in position normally by the spring 26.

Also attached to the casing plate i1 is a bracket 21 formed of an outwardly displaced metal support 28 and a slidabie member 29. The support 28 is U-shaped with a pair of parallel side plates 30 and a bridge plate 3|, the sides 30 of the U terminating in flanges 32 which are apertured to receive attachment screws 33 at either end thereof. The bridge plate 3! of the U is flat and provided with attachment screws 34 on either side thereof, these screws being adapted for holding the slidabie member 29 in any desired vertical position.

The slide member 29 consists of a central base plate 35 to the edges of which are secured by any appropriate means, angle plates 36. One section of the angle plates is coextensive with the base plate 35 and is provided with double slots 3'! through which the attachment screws 34 project for fixing the position of the angle plates and attached base plate 35. At the upper ends of the angle plates 35, as shown in Figures 1 and 2, the section thereof projecting parallel to the furnace axis is apertured to receive the shaft of the ioad roller 38. This roller as shown in Figures 2 and 3 is concave in axial section, the better to retain the load in central position thereon as it is being moved into the feed guide of the furnace.

Just below the load roller 38 and secured to the base plate 35 on the surface distant from the furnace are projecting plate members 40 which serve as an enclosure and protecting means for the switch box it. The switch box is secured to the base plate 35 by screws or other means. A conductor cable 42 leads from the base of the switch box to a terminal box 43 on the furnace casing, the cable being flexible so that the switch box may be moved without electrical disturbance or the connections. On the inner side of the slidabie support plate 35 and at the upper end thereof is mounted inwardly projecting support Bugs 44 which are designed to form the supporting means for a pivot tube 45 by means of a core pin and attachment screws El. The tube 45 is rotatable on the pin 60. To this tube, and centrally thereof, is attached a projecting arm 46. For such attachment one end of the arm is apertured and a cut 41 is made directly in the arm to the aperture from a point on the arm displaced from the aperture. Through the two sections of the arm end thus formed, that is, the short section 48 and the main arm section 46, screw means is provided to bind the two sections together and thereby clamp the arm fixedl on the tube 45.

The arm 46 is designed for limited vertical pivotal movement upon the tube 45 and for this purpose a coil spring 49 is placed on one section of the tube between the arm and the support lug 44, one end of the spring being fastened to the lug 44 and the other end hooked around the under side of the arm at a point displaced sufiiciently along the arm from the tube to secure adequate leverage. The action of the spring is to move the arm upwardly and this movement is continued until a stop member 50, secured to the tube 45, contacts against the angle plate 36 thereby limiting this movement.

The forward end of the arm 46 projects into the feed guide l4 of the furnace, there being provided in said guide a cut-away slot 5| of sumcient depth at the base of the guide inlet to per mit of adequate vertical movement of the arm end when compressed by the movement of a load into or out of the furnace. Normally, the upper end 52 of the arm, which is curved as shown in Figure 1, projects in use above the cylindrical envelope surface defined by the bearing edges of the rail support lugs 8 so that movement of the arm will be necessitated by contact with the workpiece in its movement in and out of the furnace chamber. Adjustment is, of course, made by the operator in accordance with the position of the feed guide I 4 and is accomplished by movement of the slidable member 29. In making this adjustment, the slidabie member 29 is moved until the roller 38 is in contact with the lower surface of a workpiece which has been properly centered. By so doing, the inner end of the arm 46 assumes its proper relation with the switch 4| to bring about closure of the same as indicated by the broken line 62. This will become evident on inspection of the showing of Figure 1 where it will be seen that depending from the pivoted end of the arm 46 is a switch operator support arm 53 apertured to receive a switch contact operator element 54. A lock nut 55 places the switch contact in proper position. Axialiy aligned with the switch operator element 54 is a cooperating movable switch operating element 56 also controlled in position by lock nut 51. Pressure of the switch operating element 56 by the switch operator element 54 causes closure of the switch circuit mechanism; and release of pressure on the switch operating element 55 by the switch operator element 54 causes the switch mechanism to open. The position of the arm 46 when spring-held upwardl against the stop 50 is such as to maintain the switch mechanism open and pressure of the arm downwardly to the extent of the surface defined by the feed guide causes closure of the switch mechanism.

It is therefore now apparent that since the relationshrip of the arm 46 to the switch mechanism and load support roller 38 may be fixed by proper adjustment, whenever the roller is in contact with the lower surface of the load, the arm 46 may be also correctly placed in relation to the switch 4|. Consequently, it becomes immaterial what the diameter of the load may be since correct adjustment of the switch exists if the movable bracket member 29 is moved so that the roller 38 engages the workpiece.

Variations of the specific structure shown may be made and hence no limitation is implied other than that which may be required by the claims hereto appended.

What is claimed is:

1. Bar heating apparatus comprising in com bination, an electrical heater provided with an opening for the insertion of a workpiece along the axis thereof, means for supplying heating current to said heater, a first guide for directing a workpiece along a travel axis to the opening of said heater, a second guide for directing the workpiece along said axis to said first guide and the heater, and a control element operatively associated with means {or controlling supply of heating current to said heater mounted on the second guide and extending from one side toward said axis and in the path of a workpiece in the region of said first guide and said heater opening, said element being engaged by said workpiece when the workpiece is in heating position for actuating said last mentioned means and applying and maintaining heating current in said heater.

2. Bar heating apparatus comprising in combination, an electrical heater provided with an opening for the insertion of a workpiece along the axis thereof, means for supplying heating current to said heater, a first guide for directing a workpiece along a travel axis to the opening of said heater, a second guide for directing the workpiece along said axis to said first guide and the heater, and a control element operatively associated with means for controlling supply of heating current to said heater mounted on the second guide and extending from one side toward said axis and in the path of a workpiece in the region of said first guide and said heater opening, said element being engaged by said workpiece when the workpiece is in heating position for actuating said last mentioned means and applying and maintaining heating current in said heater, said guides being adjustable in a direction transverse to said axis, and said control element being mounted for adjusting movement with said second guide.

3. Bar heating apparatus comprising in combination, an induction heating furnace of tubular shape with an axis of travel for a bar workpiece fed thereto, a plurality of guide means spaced along said axis for feeding a workpiece to said furnace. a switch mounted on one of said guide means. a switch operator also mounted with the switch on said guide means, said switch operator arm having one end extended toward said axis into one side of the path of movement of the workpiece, said switch and operator controlling the supply of current to said furnace to heat the workpiece while it engages said operator, said guide means being adjustextended toward said able relative to said axis, and said switch and operator being moved in adjustment with the guide means on which they are mounted.

4. Bar heating apparatus comprising in combination, an induction heating furnace of tubular shape with an axis of travel for a bar workpiece fed thereto, a plurality of guide means spaced along said axis for feeding a workpiece to said furnace, a switch mounted on one of said guide means, a switch operator also mounted with the switch on said guide means, said switch operator comprising an inclined arm having one end axis into one side of the path of movement of the workpiece, said switch and operator controlling the supply of current to said furnace to heat the workpiece while it engages said operator, said guide means being adjustable relative to said axis, and said switch and operator being moved in adjustment with the guide means on which they are mounted, said operator arm having its workpiece engaging end disposed within the guide means adjacent that on which it is mounted.

HAROLD A. STRICKLAND, JR.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 549,152 Pogue Nov. 5, 1895 664,371 Ayer Dec. 25, 1900 1,064,358 Mettler June 10, 1913 1,081,164 Soloman Dec. 9, 1913 1,101,527 Denhard June 30, 1914 2,365,021 Strickland Dec. 12, 1944 

